In the past, three-dimensional printing has been realized through Braille printing, a layering technique through UV ink, a physical pressing method, a three-dimensional printer and/or the like. For example, a method of forming three-dimensional images by using thermal expansion sheets made of thermal expansion microspheres of material with a low boiling point microencapsulated by thermoplastic resin, forming an image using for example black toner with a high thermal energy absorbency on this thermal expansion sheet, exposing the entire surface uniformly to strong light and selectively heating parts of the image through differences in light absorption to create a three-dimensional image has been known in Unexamined Japanese Patent Application KOKAI Publication No. S54-089638. However, with this pioneering technology, essentially no mention is made of coloring the three-dimensional image.
Hence, in Unexamined Japanese Patent Application KOKAI Publication No. 2001-150812, besides forming a planar image such as a color image on the surface of a foam sheet, a light-absorbing pattern for shaded images is formed on the back surface of the base layer of the foam sheet on the basis of distant image data in which a three-dimensional shape related to the planar image is expressed. A foam molding method is proposed through a printed foam sheet with a high degree of freedom in the bulge amount by shining light on this from the base layer side, generating heat in accordance with the shading of the image, and causing the foam sheet to expand and bulge in accordance with distant image data.
However, the conventional three-dimensional image formation methods described in the above-described Unexamined Japanese Patent Application Kokai Publication No. S54-089638 and Unexamined Japanese Patent Application Kokai Publication No. 2001-150812 have a variety of problems, such as requiring time to create three-dimensional printing, having numerous processes and requiring much labor, and accordingly, the devices become complicated and costs increase.
Not only that, but the three-dimensional image formation methods of the above-described Unexamined Japanese Patent Application KOKAI Publication No. S54-089638 and Unexamined Japanese Patent Application KOKAI Publication No. 2001-150812 all produce the image surface by first forming the image and then causing thermal expansion, so cracks can form in the surface of the image after expansion. As a result, the problem exists that the image quality of the three-dimensional image drops markedly.